Measurement of the inhomogeneity of the KATRIN tritium source electric potential by high-resolution spectroscopy of conversion electrons from 83mKr - Acharya, H; Aker, M; Batzler, D; Beglarian, A; Beisenkoetter, J; Biassoni, M; Bieringer, B; Biondi, Y; Block, F; Bornschein, B; Bornschein, L; Boettcher, M; et al. (European Physical Journal C, 2025)